Primary Total Joint Replacement Research Articles

Debulking of the Femoral Stem in a Primary Total Hip Joint Replacement: A Novel Method to Reduce Stress Shielding.

In current-generation designs of total primary hip joint replacement, the prostheses are fabricated from alloys. The modulus of elasticity of the alloy is substantially higher than that of the surrounding bone. This discrepancy plays a role in a phenomenon known as stress shielding, in which the bone bears a reduced proportion of the applied load. Stress shielding has been implicated in aseptic loosening of the implant which, in turn, results in reduction in the in vivo life of the implant. Rigid implants shield surrounding bone from mechanical loading, and the reduction in skeletal stress necessary to maintain bone mass and density results in accelerated bone loss, the forerunner to implant loosening. Femoral stems of various geometries and surface modifications, materials and material distributions, and porous structures have been investigated to achieve mechanical properties of stems closer to those of bone to mitigate stress shielding. For improved load transfer from implant to femur, the proposed study investigated a strategic debulking effort to impart controlled flexibility while retaining sufficient strength and endurance properties. Using an iterative design process, debulked configurations based on an internal skeletal truss framework were evaluated using finite element analysis. The implant models analyzed were solid; hollow, with a proximal hollowed stem; FB-2A, with thin, curved trusses extending from the central spine; and FB-3B and FB-3C, with thick, flat trusses extending from the central spine in a balanced-truss and a hemi-truss configuration, respectively. As outlined in the International Organization for Standardization (ISO) 7206 standards, implants were offset in natural femur for evaluation of load distribution or potted in testing cylinders for fatigue testing. The commonality across all debulked designs was the minimization of proximal stress shielding compared to conventional solid implants. Stem topography can influence performance, and the truss implants with or without the calcar collar were evaluated. Load sharing was equally effective irrespective of the collar; however, the collar was critical to reducing the stresses in the implant. Whether bonded directly to bone or cemented in the femur, the truss stem was effective at limiting stress shielding. However, a localized increase in maximum principal stress at the proximal lateral junction could adversely affect cement integrity. The controlled accommodation of deformation of the implant wall contributes to the load sharing capability of the truss implant, and for a superior biomechanical performance, the collared stem should be implanted in interference fit. Considering the results of all implant designs, the truss implant model FB-3C was the best model.

A systematic review and meta-analysis of antibiotic-loaded bone cement for prevention of deep surgical site infections following primary total joint replacement

BackgroundThe use of antibiotic-loaded bone cement (ALBC) as a mean for preventing deep surgical site infections (SSI) after total joint replacement is controversial. Therefore, we have conducted a meta-analysis to evaluate the prophylactic effect of ALBC for SSI prevention in patients undergoing arthroplasty. This study was conducted to revise treatment guidelines for MRSA infections in Japan. MethodsPubMed (Medline), Scopus, Embase, Web of Science and Cochrane library were searched for relevant articles comparing preventive effect of ALBC for patients undergoing primary total joint arthroplasty by August 2022. Primary outcome was the incidence of deep SSI. Subgroup analyses by type of surgery (total hip (THA) or knee (TKA) arthroplasty) and by causative pathogen (methicillin-resistant Staphylococcus aureus (MRSA)) were performed. ResultsOf the 3379 studies identified for screening, six studies involving 5745 patients were included. The use of ALBC significantly reduced the incidence of deep SSI in overall patients (risk ratio [RR] 0.60, 95% confidential interval [CI] 0.39–0.92), but the evidence level was very low. There was no significant preventive effect for ALBC compared with non-ALBC in both THA and TKA (THA, RR 0.52, 95% CI 0.23–1.16; TKA, RR 0.64, 95% CI 0.38–1.06), and for preventing MRSA-SSI (RR 0.27, 95% CI 0.03–2.41). ConclusionsAlthough the overall preventive effect of ALBC was significant, the evidence level was very low. Thus, the routine use of ALBC as a mean to prevent SSI in arthroplasty may not be suggested.

The incidence and risk factors for abnormal postoperative blood tests following primary total joint replacement.

We aim to evaluate the usefulness of postoperative blood tests by investigating the incidence of abnormal results following total joint replacement (TJR), as well as identifying preoperative risk factors for abnormal blood test results postoperatively, especially pertaining to anaemia and acute kidney injury (AKI). This is a retrospective cohort study of patients who had elective TJR between January and December 2019 at a tertiary centre. Data gathered included age at time of surgery, sex, BMI, American Society of Anesthesiologists (ASA) grade, preoperative and postoperative laboratory test results, haemoglobin (Hgb), white blood count (WBC), haematocrit (Hct), platelets (Plts), sodium (Na+), potassium (K+), creatinine (Cr), estimated glomerular filtration rate (eGFR), and Ferritin (ug/l). Abnormal blood tests, AKI, electrolyte imbalance, anaemia, transfusion, reoperation, and readmission within one year were reported. The study included 2,721 patients with a mean age of 69 years, of whom 1,266 (46.6%) were male. Abnormal postoperative bloods were identified in 444 (16.3%) patients. We identified age (≥ 65 years), female sex, and ASA grade ≥ III as risk factors for developing abnormal postoperative blood tests. Preoperative haemoglobin (≤ 127 g/dl) and packed cell volume (≤ 0.395 l/l) were noted to be significant risk factors for postoperative anaemia, and potassium (≤ 3.7 mmol/l) was noted to be a significant risk factor for AKI. The costs outweigh the benefits of ordering routine postoperative blood tests in TJR patients. Clinicians should risk-stratify their patients and have a lower threshold for ordering blood tests in patients with abnormal preoperative haemoglobin (≤ 127 g/l), blood loss > 300 ml, chronic kidney disease, ASA grade ≥ III, and clinical concern.

National variation in prophylactic antibiotic use for elective primary total joint replacement.

Prophylactic antibiotic regimens for elective primary total hip and knee arthroplasty vary widely across hospitals and trusts in the UK. This study aimed to identify antibiotic prophylaxis regimens currently in use for elective primary arthroplasty across the UK, establish variations in antibiotic prophylaxis regimens and their impact on the risk of periprosthetic joint infection (PJI) in the first-year post-index procedure, and evaluate adherence to current international consensus guidance. The guidelines for the primary and alternative recommended prophylactic antibiotic regimens in clean orthopaedic surgery (primary arthroplasty) for 109 hospitals and trusts across the UK were sought by searching each trust and hospital's website (intranet webpages), and by using the MicroGuide app. The mean cost of each antibiotic regimen was calculated using price data from the British National Formulary (BNF). Regimens were then compared to the 2018 Philadelphia Consensus Guidance, to evaluate adherence to international guidance. The primary choice and dosing of the prophylactic antimicrobial regimens varied widely. The two most used regimens were combined teicoplanin and gentamicin, and cefuroxime followed by two or three doses of cefuroxime eight-hourly, recommended by 24 centres (22.02%) each. The alternative choice and dosing of the prophylactic antimicrobial regimen also varied widely across the 83 centres with data available. Prophylaxis regimens across some centres fail to cover the likeliest causes of surgical site infection (SSI). Five centres (4.59%) recommend co-amoxiclav, which confers no Staphylococcus coverage, while 33 centres (30.28%) recommend cefuroxime, which confers no Enterococcus coverage. Limited adherence to 2018 Philadelphia Consensus Guidance was observed, with 67 centres (61.50%) not including a cephalosporin in their guidance. This analysis of guidance on antimicrobial prophylaxis in primary arthroplasty across 109 hospitals and trusts in the UK has identified widespread variation in primary and alternative antimicrobial regimens currently recommended.

Periprosthetic Joint Infection Diagnosis: A Narrative Review.

Replacement of native joints aims to restore patients' quality of life by relieving pain and improving joint function. While periprosthetic joint infection (PJI) affects a small percentage of patients, with an estimated incidence of 1-9% following primary total joint replacement, this postoperative complication necessitates a lengthy hospitalisation, extended antibiotic treatment and further surgery. It is highlighted that establishing the correct diagnosis of periprosthetic infections is critical in order for clinicians to avoid unnecessary treatments in patients with aseptic failure. Of note, the PJI diagnosis could not purely rely upon clinical manifestations given the fact that heterogeneity in host factors (e.g., age and comorbidities), variability in infection period, difference in anatomical location of the involved joint and discrepancies in pathogenicity/virulence of the causative organisms may confound the clinical picture. Furthermore, intra-operative contamination is considered to be the main culprit that can result in early or delayed infection, with the hematogenous spread being the most prevalent mode. To elaborate, early and hematogenous infections often start suddenly, whereas chronic late infections are induced by less virulent bacteria and tend to manifest in a more quiescent manner. Last but not least, viruses and fungal microorganisms exert a role in PJI pathogenesis.

Are postoperative blood tests always required after lower limb arthroplasty?

It is common practice for patients to have postoperative blood tests after total joint replacement (TJR). However, there have been significant improvements in perioperative care with arthroplasty surgery, and a drive to reduce the length of stay (LOS) and move towards day-case TJR. We should reconsider whether this intervention is necessary for all patients. This retrospective study included all patients who underwent a primary unilateral TJR at a single tertiary arthroplasty centre during a one-year period. Electronic medical records of 1,402 patients were reviewed for patient demographics, LOS, and American Society of Anesthesiologists (ASA) grade. Blood tests were examined to investigate the incidence of postoperative anaemia, electrolyte abnormalities, and incidence of acute kidney injury (AKI). For total knee arthroplasties, preoperative (R = -0.22) and postoperative haemoglobin (R = 0.2) levels were both negatively correlated with LOS (p < 0.001). For all patients who had undergone a TJR, 19 patients (0.014%) required a blood transfusion postoperatively due to symptomatic anaemia. Risk factors identified were age, preoperative anaemia, and long-term aspirin use. Significant abnormal sodium levels were found in123 patients (8.7%). However, only 36 patients (2.6%) required intervening treatment. Risk factors identified were age, preoperative abnormal sodium level, and long-term use of non-steroidal anti-inflammatory drugs, angiotensin receptor blockers, and corticosteroids. Similarly, abnormal potassium levels were evident in 53 patients (3.8%), and only 18 patients (1.3%) required intervening treatment. Risk factors identified were preoperative abnormal potassium level, and long-term use of angiotensin-converting enzyme inhibitors and diuretics. The incidence of AKI was 4.4% (61 patients). Risk factors identified were age, increased ASA grade, preoperative abnormal sodium, and creatinine level. Routine blood tests after primary TJR is unnecessary for most patients. Blood tests should only be performed on those with identifiable risk factors such as preoperative anaemia and electrolyte abnormalities, haematological conditions, long-term aspirin use, and electrolyte-altering medications.

Effect of non-cephalosporin antibiotic prophylaxis on the risk of periprosthetic joint infection after total joint replacement surgery: a retrospective study with a 1-year follow-up

Cephalosporins are recommended as first-line antibiotic prophylaxis in total joint replacement surgery. Studies have shown an increased risk for periprosthetic joint infection (PJI) when non-cephalosporin antibiotics have been used. This study examines the effect of non-cephalosporin antibiotic prophylaxis on the risk for PJI. Patients with a primary hip or knee replacement performed from 2012 to 2020 were identified (27 220 joint replacements). The primary outcome was the occurrence of a PJI in a one-year follow-up. The association between perioperative antibiotic prophylaxis and the outcome was examined using logistic regression analysis. Cefuroxime was used as prophylaxis in 26,467 operations (97.2%), clindamycin in 654 (2.4%) and vancomycin in 72 (0.3%). The incidence of PJI was 0.86% (228/26,467) with cefuroxime and 0.80% (6/753) with other prophylactic antibiotics. There was no difference in the risk for PJI with different prophylactic antibiotics in the univariate (OR 1.06, 95% CI 0.47-2.39) or multivariable analysis (OR 1.02, 95% CI 0.45-2.30). Non-cephalosporin antibiotic prophylaxis in primary total joint replacement surgery was not associated with an increased risk for PJI.

CEMENTED VERSUS UNCEMENTED KNEE JOINT ARTHROPLASTIES: FIVE-YEAR FOLLOW-UP COMPARING FUNCTIONAL OUTCOMES AND REVISION RATES

Our objective was to examine revision rates and patient reported outcome scores (PROMS) for cemented and uncemented primary total knee joint replacement (TKJR) at six months, one year and five years post-operatively. Patients and Methods: This matched cohort study involved secondary analyses of data collected as part of a large prospective observational study monitoring outcomes following knee replacement in Christchurch, New Zealand. Cemented and uncemented TKJR participants (n = 1526) were matched on age (± 5 years), sex and body mass index (BMI). From this larger sample, PROMS data, Oxford Knee Score and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), out to five years post-operatively were analysed for a matched subset of participants (n = 252).The average age of participants was 67.9 years (SD 9.4, range 38-94). There were no differences between cemented and uncemented cohorts on the basis of age, sex, BMI or comorbidities, revision rates or PROMS outcomes. Cemented procedures had greater skin to skin times than uncemented procedures (p &lt; 0.01). Unadjusted outcomes comparing risk for revision across the two participant cohorts did not significantly differ. Overall rates for revision were low (cemented 3.2% v uncemented 2.7%, p=0.70). Propensity adjusted associations between baseline characteristics (age, sex, BMI, comorbidity, baseline Oxford and baseline WOMAC scores) also revealed no differences in risk for revision at any post-operative timepoint.In this large multi-surgeon matched cohort study there were no significant differences in functional outcomes or revision rates, when outcomes following modern cemented and uncemented TKJR were compared out to 5-year follow up. Based on our findings, uncemented TKJR is predictable irrespective of patient's age, BMI or gender

Delay of total joint replacement is associated with a higher 90-day revision rate and increased postoperative complications

PurposeDelay of elective surgeries, such as total joint replacement (TJR), is a common procedure in the current pandemic. In trauma surgery, postponement is associated with increased complication rates. This study aimed to evaluate the impact of postponement on surgical revision rates and postoperative complications after elective TJR.MethodsIn a retrospective analysis of 10,140 consecutive patients undergoing primary total hip replacement (THR) or total knee replacement (TKR) between 2011 and 2020, the effect of surgical delay on 90-day surgical revision rate, as well as internal and surgical complication rates, was investigated in a university high-volume arthroplasty center using the institute’s joint registry and data of the hospital administration. Moreover, multivariate logistic regression models were used to adjust for confounding variables.ResultsTwo thousand four hundred and eighty TJRs patients were identified with a mean delay of 13.5 ± 29.6 days. Postponed TJR revealed a higher 90-day revision rate (7.1–4.5%, p < 0.001), surgical complications (3.2–1.9%, p < 0.001), internal complications (1.8–1.2% p < 0.041) and transfusion rate (2.6–1.8%, p < 0.023) than on-time TJR. Logistic regression analysis confirmed delay of TJRs as independent risk factor for 90-day revision rate [OR 1.42; 95% CI (1.18–1.72); p < 0.001] and surgical complication rates [OR 1.51; 95% CI (1.14–2.00); p = 0.04].ConclusionAlike trauma surgery, delay in elective primary TJR correlates with higher revision and complication rates. Therefore, scheduling should be performed under consideration of the current COVID-19 pandemic.Level of evidenceLevel III—retrospective cohort study.

CO81 Episode of Care Assurance Program (ECAP) Results in Significantly Reduced Readmissions for Patients Undergoing Primary Total Joint Replacement Surgery

The leading cause of total joint arthroplasty (TJA) readmission is wound complications with national average readmission rate of 5.3%, and mean cost of $27,979 per hospital stay. The study aimed to evaluate the impact of eCAP, a warranty system for using Smith+Nephew’s Primary Total Hip or Knee System with Oxinium + Single Use Negative Pressure Wound Therapy + Antimicrobial Silver Dressing together in 44 hospital facilities who have implemented it, compared to non-eCAP facilities for readmissions in patients undergoing primary TJA surgery.

Effects of Hypercarbia on Lower Extremity Primary Total Joint Replacement Infections.

Introduction: Prosthetic joint infection (PJI) is a serious complication after total joint replacement (TJR). Adequate wound oxygenation is critical for wound healing and infection prevention. As carbon dioxide (CO2) is exchanged for oxygen (O2) in the lungs, serum bicarbonate (HCO3-) may be used as a marker for predicting relative serum O2 levels, and therefore, healing potential. No currently published literature explores the relationship between serum bicarbonate levels and PJI in TJR patients.Methods: We performed this retrospective review of lower extremity TJR patients to determine whether the risk of PJI and wound complications within one year was correlated with hypercarbia, which was defined as a preoperative serum bicarbonate level >30 mEq/L.Results: Out of 1,690 TJR procedures, 1.6% (N=27) had a PJI or superficial wound infection within one year postoperatively. The average preoperative serum bicarbonate was 26.9 (SD 2.6) among patients without PJI and 27.2 (SD 2.1) among patients with PJI (p=0.46). Hypercarbia was present in 9.2% of non-PJI patients and in 7.4% of PJI patients. The relative risk of PJI and wound complications did not differ for patients with vs without hypercarbia (RR = 0.79, 95% CI = 0.19-3.31, p=0.75).Conclusion: The results of this study provide preliminary evidence that preoperative hypercarbia may not be correlated with an increase in the risk of PJI or wound complications. However, due to the rarity of both PJI and hypercarbia, a larger patient population is needed to ensure adequate power to detect clinically meaningful effect sizes.

Low incidence of clinically relevant bleeding complications after fast-track arthroplasty: a register study of 8,511 arthroplasties.

Background and purposeFast-track total joint replacement (TJR) has become increasingly common. Routine thromboprophylaxis for pulmonary embolism and deep venous thrombosis prevention lasts from 2 to 5 weeks. This retrospective registry study focused on clinically relevant bleeding complications 90 days after fast-track primary TJR.Patients and methodsAll primary fast-track total hip (THA) and knee arthroplasties (TKA) performed between 2015 and 2016 were extracted from the Finnish Arthroplasty Register and Finnish Hospital Discharge Register. Type of arthroplasty and indication for the operation were combined with diagnoses of clinically relevant bleeding complications within 90 days of surgery. The incidence of these bleedings was the primary outcome measure.ResultsOf the total of 8,511 patients (mean age 67 years (SD 10); 60% female), 45% underwent unilateral THA, 52% unilateral TKA, and 3% bilateral TKA. The incidence of clinically relevant bleeding complications within 90 days was 1% (95% CI 0.8–1.3). No difference was observed in bleeding incidence between the groups. The 87 bleedings comprised 57 operative site bleedings, 17 gastrointestinal bleedings, 6 intracranial non-traumatic bleedings, 5 bleedings from the nose or another undetermined site, and 2 intraocular bleedings. 1 death due to intracranial bleeding was recorded, and hence clinically relevant bleeding-specific 90-day mortality was 0.01%.InterpretationThe incidence of clinically relevant bleeding complications was low. However, they cause patient discomfort, increase the use of healthcare services, and can be life-threatening and even fatal.

Current Concepts on the Application, Pharmacokinetics and Complications of Antibiotic-Loaded Cement Spacers in the Treatment of Prosthetic Joint Infections.

Prosthetic joint infection (PJI) is a devastating complication of total joint replacement surgery. It affects about 2% of primary total joint replacements. Treatment aims at infection eradication and restoration of patient's mobility. Two-stage revision arthroplasty with an interim application of an antibiotic-loaded cement spacer (ALCS) is the widely accepted treatment for PJI. Spacers are powerful local carriers of antibiotics at the site of infection, effective against biofilm-protected microbes. On the other hand, spacers permit some mobility of the patient and facilitate final prosthesis implantation. ALCS's are either commercially available or prepared intraoperatively on prefabricated or improvised molds. Antibiotic elution from the spacer depends on the amount of the antibiotic used for cement impregnation, at the expense of mechanical stiffness of the spacer. The antibiotic should not exceed 4g per 40g of bone cement to preserve the mechanical properties of the cement. Spacers are frequently accompanied by local or systemic complications. The spacer may break, dislocate and compress vessels or nerves of the limb. Systemic complications are the result of excess elution of antibiotic and include nephrotoxicity, hepatotoxicity, ototoxicity, allergic reactions or neutropenia. Elderly patients with comorbidities are at risk to present such complications. Microbial resistance is a potential risk of long-lasting spacer retention. Persisting infection may require multiple spacer replacements.

Non-compliance with clinical guidelines increases the risk of complications after primary total hip and knee joint replacement surgery.

Total hip and total knee replacement (THR/TKR) are common and effective surgeries to reduce the pain and disability associated with arthritis but are associated with small but significant risks of preventable complications such as surgical site infection (SSI) and venous-thrombo-embolism (VTE). This study aims to determine the degree to which hospital care was compliant with clinical guidelines for the prevention of SSI and VTE after THR/TKR; and whether non-compliant prophylaxis is associated with increased risk of complications. A prospective multi-centre cohort study was undertaken in consenting adults with osteoarthritis undergoing elective primary TKR/THR at one of 19 high-volume Australian public or private hospitals. Data were collected prior to surgery and for one-year post-surgery. Four adjusted logistic regression analyses were undertaken to explore associations between binary non-compliance and the risk of surgical complications: (1) composite (simultaneous) non-compliance with both (VTE and antibiotic) guidelines and composite complications [all-cause mortality, VTE, readmission/reoperation for joint-related reasons (one-year) and non-joint-related reasons (35-days)], (2) VTE non-compliance and VTE outcomes, (3) antibiotic non-compliance and any SSI, and (4) antibiotic non-compliance and deep SSI. Data were analysed for 1875 participants. Guideline non-compliance rates were high: 65% (VTE), 87% (antibiotics) and 95% (composite guideline). Composite non-compliance was not associated with composite complication (12.8% vs 8.3%, adjusted odds ratio [AOR] = 1.41, 95%CI 0.68-3.45, p = 0.40). Non-compliance with VTE guidelines was associated with VTE outcomes (5% vs 2.4%, AOR = 2.83, 95%CI 1.59-5.28,p < 0.001). Non-compliance with antibiotic guidelines was associated with any SSI (14.8% vs 6.1%, AOR = 1.98, 95%CI 1.17-3.62,p = 0.02) but not deep infection (3.7% vs 1.2%,AOR = 2.39, 95%CI 0.85-10.00, p = 0.15). We found high rates of clinical variation and statistically significant associations between non-compliance with VTE and antibiotic guidelines and increased risk of VTE and SSI, respectively. Complications after THR/TKR surgery may be decreased by improving compliance with clinical guidelines.

A Bioglass-Based Antibiotic (Vancomycin) Releasing Bone Void Filling Putty to Treat Osteomyelitis and Aid Bone Healing.

While the infection rate after primary total joint replacements (TJR) sits at 1–2%, for trauma-related surgery, it can be as high as 3.6 to 21.2% based on the type of trauma; the risk of reinfection after revision surgery is even higher. Current treatments with antibiotic-releasing PMMA-based bone cement/ beads and/or systemic antibiotic after surgical debridement do not provide effective treatment due to fluctuating antibiotic levels at the site of infection, leading to insufficient local antibiotic concentration. In addition, non-biodegradable PMMA does not support bone regrowth in the debrided void spaces and often must be removed in an additional surgery. Here, we report a bioactive glass or bioglass (BG) substrate-based biodegradable, easy to fabricate “press fitting” antibiotic-releasing bone void filling (ABVF-BG) putty to provide effective local antibiotic release at the site of infection along with support for bone regeneration. The ABVF-BG putty formulation had homogenously distributed BG particles, a porous structure, and showed putty-like ease of handling. Furthermore, the ABVF-BG putty demonstrated in vitro antibacterial activity for up to 6 weeks. Finally, the ABVF-BG putty was biodegradable in vivo and showed 100% bacterial eradication (as shown by bacterial cell counts) in the treatment group, which received ABVF-BG putty, compared to the infection control group, where all the rats had a high bacterial load (4.63 × 106 ± 7.9 × 105 CFU/gram bone) and sustained osteomyelitis. The ABVF-BG putty also supported bone growth in the void space as indicated by a combination of histology, µCT, and X-ray imaging. The potential for simultaneous infection treatment and bone healing using the developed BG-based ABVF-BG putty is promising as an alternative treatment option for osteomyelitis.

Body Mass Index Differentially Moderates Heritability of Total Joint Replacement Due to Hip and Knee Osteoarthritis: A Cohort Study of 29,893 Swedish Twin Pairs.

Osteoarthritis and obesity are diseases with high prevalence, and they share common etiologies. We investigated the sex-specific genetic susceptibility to hip and knee osteoarthritis necessitating total joint replacement (TJR), and how body mass index (BMI) moderated the heritability of these osteoarthritis phenotypes. We linked 29,893 twin pairs with information on BMI in the Swedish Twin Registry with the Swedish National Patient Register to identify twins who underwent primary TJR of the hip or knee combined with a concomitant diagnosis of primary osteoarthritis of these joints. Structural equation modeling was used to calculate the heritability of hip and knee osteoarthritis treated with TJR, with estimates adjusted for the first available BMI, birth year, and sex. We also investigated how heritability varied with BMI treated as a continuous variable. Similar heritability estimates for hip replacement (0.65 [95% confidence interval (CI), 0.59 to 0.70]) and knee replacement (0.57 [95% CI, 0.50 to 0.64]) were found. Heritability decreased with higher BMI in both sexes for hip replacement and in men for knee replacement. In contrast, heritability for knee replacement increased with higher BMI in women; the estimate was 0.37 (90% likelihood interval [LI], 0.25 to 0.49) for a BMI of 20 kg/m2 and 0.87 (90% LI, 0.68 to 0.94) for a BMI of 35 kg/m2. In our population, heritability explained, on average, about half of the susceptibility to undergo primary TJR of the hip or knee with the indication of primary osteoarthritis, but it varied with BMI and sex. We demonstrated substantial heritability for knee replacement in obese women. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Postdischarge Opioid Use after Total Hip and Total Knee Arthroplasty.

BackgroundAs America’s third highest opioid prescribers, orthopedic surgeons have contributed to the opioid abuse crisis. This study evaluated opioid use after primary total joint replacement. We hypothesized that patients who underwent total hip arthroplasty (THA) use fewer opioids than patients who underwent total knee arthroplasty (TKA) and that both groups use fewer opioids than prescribed.MethodsA prospective study of 110 patients undergoing primary THA or TKA by surgeons at an academic center during 2018 was performed. All were prescribed oxycodone 5 mg, 84 tablets, without refills. Demographics, medical history, and operative details were collected. Pain medication consumption and patient-reported outcomes were collected at 2 and 6 weeks postoperatively. Analysis of variance was performed on patient and surgical variables.ResultsSixty-one patients scheduled for THA and 49 for TKA were included. THA patients consumed significantly fewer opioids than TKA patients at 2 weeks (28.1 tablets vs 48.4, P = .0003) and 6 weeks (33.1 vs 59.3, P = .0004). Linear regression showed opioid use decreased with age at both time points (P = .0002). A preoperative mental health disorder was associated with higher usage at 2 weeks (58.3 vs 31.4, P < .0001) and 6 weeks (64.7 vs 39.2, P = .006). Higher consumption at 2 weeks was correlated with worse outcome scores at all time points.ConclusionsTKA patients required more pain medication than THA patients, and both groups received more opioids than necessary. In addition, younger patients and those with a preexisting mental health disorder required more pain medication. These data provide guidance on prescribing pain medication to help limit excess opioid distribution.

Can an outpatient risk assessment tool predict who needs postoperative haemoglobin monitoring?

Recent improvements in surgical technique and perioperative blood management after total joint replacement (TJR) have decreased rates of transfusion. However, as many surgeons transition to outpatient TJR, obtaining routine postoperative blood tests becomes more challenging. Therefore, we sought to determine if a preoperative outpatient assessment tool that stratifies patients based on numerous medical comorbidities could predict who required postoperative haemoglobin (Hb) measurement. We performed a prospective study of consecutive unilateral primary total knee arthroplasties (TKAs) and total hip arthroplasties (THAs) performed at a single institution. Prospectively collected data included preoperative and postoperative Hb levels, need for blood transfusion, length of hospital stay, and Outpatient Arthroplasty Risk Assessment (OARA) score. A total of 504 patients met inclusion criteria. Mean age at time of arthroplasty was 65.3 years (SD 10.2). Of the patients, 216 (42.9%) were THAs and 288 (57.1%) were TKAs. Six patients required a blood transfusion postoperatively (1.19%). Transfusion after surgery was associated with lower postoperative day 1 Hb (median of 8.5 (interquartile range (IQR) 7.9 to 8.6) vs 11.3 (IQR 10.4 to 12.2); p < 0.001), longer length of stay (1 day (IQR 1 to 1) vs 2 days (IQR 2 to 3); p < 0.001), higher OARA score (median of 60.0 (IQR 40 to 75) vs 5.0 (IQR 0-35); p = 0.001), and total hip arthroplasty (p < 0.001). All patients who received a transfusion had an OARA score > 34; however, this did not reach statistical significance as a screening threshold. Risk of blood transfusion after primary TJR was uncommon in our series, with an incidence of 1.19%. Transfusion was associated with OARA scores > 60. The OARA score, not American Society of Anesthesiologists grade, reliably identified patients at risk for postoperative blood transfusion. Selective Hb monitoring may result in substantial cost savings in the era of cost containment. Cite this article: Bone Joint J 2021;103-B(1):65-70.

Investigation of Cytotoxicity, Oxidative Stress, and Inflammatory Responses of Tantalum Nanoparticles in THP-1-Derived Macrophages.

Tantalum (Ta) is gaining attention as a biomaterial in bone tissue engineering. Although the clinical advantage of Ta-based implants for primary and revision total joint replacement (TJA) has been well documented, few studies investigated the effect of wear products of Ta implants on peri-implant cells, and their potential contribution to aseptic implant loosening. This study is aimed at examining the cytotoxicity, oxidative stress, and proinflammatory potential of Ta and TiO2 nanoparticles (NPs) on macrophages in vitro. NPs were characterized using scanning electron microscopy, dynamic light scattering, and energy-dispersive X-ray. To test the NP-mediated cellular response in macrophages, THP-1-derived macrophages were challenged with both NPs, and cytotoxicity was analyzed using CCK-8 and LDH assays. Flow cytometry was used to investigate particle uptake and their internalization routes. NP-mediated oxidative stress was investigated by measuring the production of reactive oxygen species, and their proinflammatory potential was determined by quantifying the production of TNFα and IL-1β in cell culture supernatants using ELISA. We found that both Ta and TiO2 NPs were taken up through actin-dependent phagocytosis, although TiO2 NPs did also show some involvement of macropinocytosis and clathrin-mediated endocytosis. Ta NPs caused no apparent toxicity, while TiO2 NPs demonstrated significant cytotoxicity at a concentration of over 100μg/mL at 24 h. Ta NPs induced negligible ROS generation and proinflammatory cytokines (TNFα, IL-1β) in macrophages. In contrast, TiO2 NPs markedly induced these effects in a dose-dependent manner. Our findings indicate that Ta NPs are inert, nontoxic, and noninflammatory. Therefore, Ta could be considered an excellent biomaterial in primary and revision joint arthroplasty implants.

Outcome of Debridement, Antibiotics, and Implant Retention With Modular Component Exchange in Acute Culture-Negative Periprosthetic Joint Infections

BackgroundModular component exchange and culture-directed antibiotic treatment is routinely employed for acute periprosthetic joint infection (PJI). However, as many as 7%-23% of PJIs have been reported to yield negative culture results. The efficacy of debridement, antibiotics, and implant retention (DAIR) with modular component exchange in the setting of acute culture negative PJI remains largely unknown. The aim of our study is to evaluate the outcomes of DAIR with modular component exchange in acute culture-positive and culture-negative PJI. MethodsA total of 149 consecutive patients with primary total joint replacements (90 total knee arthroplasties and 59 total hip arthroplasties) who underwent DAIR with modular component exchange for acute PJI with at least 3 years of follow-up were evaluated: (1) 46 culture-negative PJI patients and (2) 103 culture-positive PJI patients. Reinfection and aseptic revision rates along with complication rates were compared. ResultsThe reinfection rate for DAIR in acute culture-negative PJI was 13.0% compared to 19.4% in culture-positive PJI (P = .48). Mean survival time from reinfection between culture-negative (7.7 ± 0.4 years) and culture-positive (7.4 ± 0.3 years) PJI groups did not differ significantly (P = .40). Aseptic revision rates were 8.7% and 4.9% (P = .46), respectively, with loosening being the primary reason for implant failure in both cohorts. ConclusionsDespite lack of an identifying organism to guide postoperative antibiotic therapy, DAIR with modular component exchange for acute culture-negative PJI was associated with similar reinfection rates compared to acute culture-positive PJI, suggesting that culture negativity may not be a contraindication to DAIR in patients with acute PJI.